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112-639: IBM considered monolithic integrated circuit technology too immature at the time. SLT was a revolutionary technology for 1964, with much higher circuit densities and improved reliability over earlier packaging techniques such as the Standard Modular System . It helped propel the IBM System/360 mainframe family to overwhelming success during the 1960s. SLT research produced ball chip assembly, wafer bumping , trimmed thick-film resistors, printed discrete functions, chip capacitors and one of

224-492: A design flow that engineers use to design, verify, and analyze entire semiconductor chips. Some of the latest EDA tools use artificial intelligence (AI) to help engineers save time and improve chip performance. Integrated circuits can be broadly classified into analog , digital and mixed signal , consisting of analog and digital signaling on the same IC. Digital integrated circuits can contain billions of logic gates , flip-flops , multiplexers , and other circuits in

336-627: A fabrication facility (commonly known as a semiconductor fab ) can cost over US$ 12 billion to construct. The cost of a fabrication facility rises over time because of increased complexity of new products; this is known as Rock's law . Such a facility features: ICs can be manufactured either in-house by integrated device manufacturers (IDMs) or using the foundry model . IDMs are vertically integrated companies (like Intel and Samsung ) that design, manufacture and sell their own ICs, and may offer design and/or manufacturing (foundry) services to other companies (the latter often to fabless companies ). In

448-509: A microchip , computer chip , or simply chip , is a small electronic device made up of multiple interconnected electronic components such as transistors , resistors , and capacitors . These components are etched onto a small piece of semiconductor material, usually silicon . Integrated circuits are used in a wide range of electronic devices, including computers , smartphones , and televisions , to perform various functions such as processing and storing information. They have greatly impacted

560-412: A microprocessor will have memory on the chip. (See the regular array structure at the bottom of the first image. ) Although the structures are intricate – with widths which have been shrinking for decades – the layers remain much thinner than the device widths. The layers of material are fabricated much like a photographic process, although light waves in the visible spectrum cannot be used to "expose"

672-422: A silicon wafer . The process begins with a photosensitive material, called a photoresist , being applied to the substrate. A photomask that contains the desired pattern is then placed over the photoresist. Light is shone through the photomask, exposing the photoresist in certain areas. The exposed areas undergo a chemical change, making them either soluble or insoluble in a developer solution. After development,

784-466: A common active area, but there was no electrical isolation to separate them from each other. The monolithic integrated circuit chip was enabled by the inventions of the planar process by Jean Hoerni and p–n junction isolation by Kurt Lehovec . Hoerni's invention was built on Carl Frosch and Lincoln Derick's work on surface protection and passivation by silicon dioxide masking and predeposition, as well as Fuller, Ditzenberger's and others work on

896-561: A common substrate in a three-stage amplifier arrangement. Jacobi disclosed small and cheap hearing aids as typical industrial applications of his patent. An immediate commercial use of his patent has not been reported. Another early proponent of the concept was Geoffrey Dummer (1909–2002), a radar scientist working for the Royal Radar Establishment of the British Ministry of Defence . Dummer presented

1008-417: A computerized data file. This data file is converted to a series of polygons and written onto a square of fused quartz substrate covered with a layer of chromium using a photolithographic process. A laser beam (laser writer) or a beam of electrons (e-beam writer) is used to expose the pattern defined by the data file and travels over the surface of the substrate in either a vector or raster scan manner. Where

1120-490: A few card types had just discrete components and no modules. Cards plug into boards which are connected to form gates which form frames. SLT voltage levels, logic low to logic high, varied by circuit speed: The same basic packaging technology (both device and module) was also used for the devices that replaced SLT as IBM gradually transitioned to the use of monolithic integrated circuits: Monolithic integrated circuit An integrated circuit ( IC ), also known as

1232-491: A few square millimeters. The small size of these circuits allows high speed, low power dissipation, and reduced manufacturing cost compared with board-level integration. These digital ICs, typically microprocessors , DSPs , and microcontrollers , use boolean algebra to process "one" and "zero" signals . Among the most advanced integrated circuits are the microprocessors or " cores ", used in personal computers, cell-phones, etc. Several cores may be integrated together in

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1344-430: A highly water repellent layer not unlike the layer of wax on a car's paint. This water repellent layer prevents the aqueous developer from penetrating between the photoresist layer and the wafer's surface, thus preventing so-called lifting of small photoresist structures in the (developing) pattern. In order to ensure the development of the image, it is best covered and placed over a hot plate and let it dry while stabilizing

1456-408: A layer of material, as they would be too large for the features. Thus photons of higher frequencies (typically ultraviolet ) are used to create the patterns for each layer. Because each feature is so small, electron microscopes are essential tools for a process engineer who might be debugging a fabrication process. Each device is tested before packaging using automated test equipment (ATE), in

1568-435: A more durable protecting layer in future ion implantation , wet chemical etching , or plasma etching . From preparation until this step, the photolithography procedure has been carried out by two machines: the photolithography stepper or scanner, and the coater/developer. The two machines are usually installed side by side, and are "linked" together. In etching, a liquid ("wet") or plasma ("dry") chemical agent removes

1680-428: A number of steps for the p–n junction isolation of transistors on a chip, MOSFETs required no such steps but could be easily isolated from each other. Its advantage for integrated circuits was pointed out by Dawon Kahng in 1961. The list of IEEE milestones includes the first integrated circuit by Kilby in 1958, Hoerni's planar process and Noyce's planar IC in 1959. The earliest experimental MOS IC to be fabricated

1792-464: A photomask in direct contact with the wafer and exposes it to a uniform light. A proximity aligner puts a small gap of around 5 microns between the photomask and wafer. In both cases, the mask covers the entire wafer, and simultaneously patterns every die. Contact printing/lithography is liable to damage both the mask and the wafer, and this was the primary reason it was abandoned for high volume production. Both contact and proximity lithography require

1904-435: A photoresist is no longer needed, it must be removed from the substrate. This usually requires a liquid "resist stripper", which chemically alters the resist so that it no longer adheres to the substrate. Alternatively, the photoresist may be removed by a plasma containing oxygen , which oxidizes it. This process is called plasma ashing and resembles dry etching. The use of 1-Methyl-2-pyrrolidone (NMP) solvent for photoresist

2016-420: A process known as wafer testing , or wafer probing. The wafer is then cut into rectangular blocks, each of which is called a die . Each good die (plural dice , dies , or die ) is then connected into a package using aluminium (or gold) bond wires which are thermosonically bonded to pads , usually found around the edge of the die. Thermosonic bonding was first introduced by A. Coucoulas which provided

2128-421: A rate predicted by Moore's law , leading to large-scale integration (LSI) with hundreds of transistors on a single MOS chip by the late 1960s. Following the development of the self-aligned gate (silicon-gate) MOSFET by Robert Kerwin, Donald Klein and John Sarace at Bell Labs in 1967, the first silicon-gate MOS IC technology with self-aligned gates , the basis of all modern CMOS integrated circuits,

2240-407: A reliable means of forming these vital electrical connections to the outside world. After packaging, the devices go through final testing on the same or similar ATE used during wafer probing. Industrial CT scanning can also be used. Test cost can account for over 25% of the cost of fabrication on lower-cost products, but can be negligible on low-yielding, larger, or higher-cost devices. As of 2022 ,

2352-426: A semiconductor to modulate its electronic properties. Doping is the process of adding dopants to a semiconductor material. Since a CMOS device only draws current on the transition between logic states , CMOS devices consume much less current than bipolar junction transistor devices. A random-access memory is the most regular type of integrated circuit; the highest density devices are thus memories; but even

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2464-543: A similar process can be used to protect the germanium in the transistors and even pattern the surface with light. During development, Lathrop and Nall were successful in creating a 2D miniaturized hybrid integrated circuit with transistors using this technique. In 1958, during the IRE Professional Group on Electron Devices (PGED) conference in Washington, D.C., they presented the first paper to describe

2576-859: A single IC or chip. Digital memory chips and application-specific integrated circuits (ASICs) are examples of other families of integrated circuits. In the 1980s, programmable logic devices were developed. These devices contain circuits whose logical function and connectivity can be programmed by the user, rather than being fixed by the integrated circuit manufacturer. This allows a chip to be programmed to do various LSI-type functions such as logic gates , adders and registers . Programmability comes in various forms – devices that can be programmed only once , devices that can be erased and then re-programmed using UV light , devices that can be (re)programmed using flash memory , and field-programmable gate arrays (FPGAs) which can be programmed at any time, including during operation. Current FPGAs can (as of 2016) implement

2688-532: A single die. A technique has been demonstrated to include microfluidic cooling on integrated circuits, to improve cooling performance as well as peltier thermoelectric coolers on solder bumps, or thermal solder bumps used exclusively for heat dissipation, used in flip-chip . The cost of designing and developing a complex integrated circuit is quite high, normally in the multiple tens of millions of dollars. Therefore, it only makes economic sense to produce integrated circuit products with high production volume, so

2800-495: A single layer on one side of a chip of silicon in a flat two-dimensional planar process . Researchers have produced prototypes of several promising alternatives, such as: As it becomes more difficult to manufacture ever smaller transistors, companies are using multi-chip modules / chiplets , three-dimensional integrated circuits , package on package , High Bandwidth Memory and through-silicon vias with die stacking to increase performance and reduce size, without having to reduce

2912-498: A single step, quickly and with relatively low cost. In complex integrated circuits, a wafer may go through the photolithographic cycle as many as 50 times. It is also an important technique for microfabrication in general, such as the fabrication of microelectromechanical systems . However, photolithography cannot be used to produce masks on surfaces that are not perfectly flat. And, like all chip manufacturing processes, it requires extremely clean operating conditions. Photolithography

3024-486: A six-pin device. Radios with the Loewe 3NF were less expensive than other radios, showing one of the advantages of integration over using discrete components , that would be seen decades later with ICs. Early concepts of an integrated circuit go back to 1949, when German engineer Werner Jacobi ( Siemens AG ) filed a patent for an integrated-circuit-like semiconductor amplifying device showing five transistors on

3136-560: A time (single wafer processing) to improve process control. In 1957 Jules Andrus patented a photolitographic process for semiconductor fabrication, while working at Bell Labs. At the same time Moe Abramson and Stanislaus Danko of the US Army Signal Corps developed a technique for printing circuits. In 1952, the U.S. military assigned Jay W. Lathrop and James R. Nall at the National Bureau of Standards (later

3248-505: A year after Kilby, Robert Noyce at Fairchild Semiconductor invented the first true monolithic IC chip. More practical than Kilby's implementation, Noyce's chip was made of silicon , whereas Kilby's was made of germanium , and Noyce's was fabricated using the planar process , developed in early 1959 by his colleague Jean Hoerni and included the critical on-chip aluminum interconnecting lines. Modern IC chips are based on Noyce's monolithic IC, rather than Kilby's. NASA's Apollo Program

3360-521: Is a coefficient that encapsulates process-related factors and typically equals 0.4 for production. ( k 1 {\displaystyle \,k_{1}} is actually a function of process factors such as the angle of incident light on a reticle and the incident light intensity distribution. It is fixed per process.) The minimum feature size can be reduced by decreasing this coefficient through computational lithography . According to this equation, minimum feature sizes can be decreased by decreasing

3472-460: Is a subclass of microlithography , the general term for processes that generate patterned thin films. Other technologies in this broader class include the use of steerable electron beams , or more rarely, nanoimprinting , interference , magnetic fields , or scanning probes . On a broader level, it may compete with directed self-assembly of micro- and nanostructures. Photolithography shares some fundamental principles with photography in that

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3584-412: Is another method used to remove an image. When the resist has been dissolved, the solvent can be removed by heating to 80 °C without leaving any residue. Exposure systems typically produce an image on the wafer using a photomask . The photomask blocks light in some areas and lets it pass in others. ( Maskless lithography projects a precise beam directly onto the wafer without using a mask, but it

3696-413: Is approximately the square root of the product of the wavelength and the gap distance. Hence, except for projection lithography (see below), contact printing offers the best resolution, because its gap distance is approximately zero (neglecting the thickness of the photoresist itself). In addition, nanoimprint lithography may revive interest in this familiar technique, especially since the cost of ownership

3808-476: Is considered an extremely undesirable contaminant in MOSFET fabrication because it degrades the insulating properties of gate oxides (specifically, sodium ions can migrate in and out of the gate, changing the threshold voltage of the transistor and making it harder or easier to turn the transistor on over time). Metal-ion-free developers such as tetramethylammonium hydroxide (TMAH) are now used. The temperature of

3920-416: Is designed to operate with a specific gas mixture; therefore, changing wavelength is not a trivial matter, as the method of generating the new wavelength is completely different, and the absorption characteristics of materials change. For example, air begins to absorb significantly around the 193 nm wavelength; moving to sub-193 nm wavelengths would require installing vacuum pump and purge equipment on

4032-441: Is expected to be low; however, the shortcomings of contact printing discussed above remain as challenges. Very-large-scale integration (VLSI) lithography uses projection systems. Unlike contact or proximity masks, which cover an entire wafer, projection masks (known as "reticles") show only one die or an array of dies (known as a "field") in a portion of the wafer at a time. Projection exposure systems (steppers or scanners) project

4144-496: Is high because the IC's components switch quickly and consume comparatively little power because of their small size and proximity. The main disadvantage of ICs is the high initial cost of designing them and the enormous capital cost of factory construction. This high initial cost means ICs are only commercially viable when high production volumes are anticipated. An integrated circuit is defined as: A circuit in which all or some of

4256-525: Is much more sensitive to PEB time, temperature, and delay, as the resist works by creating acid when it is hit by photons, and then undergoes an "exposure" reaction (creating acid, making the polymer soluble in the basic developer, and performing a chemical reaction catalyzed by acid) which mostly occurs in the PEB. The develop chemistry is delivered on a spinner, much like photoresist. Developers originally often contained sodium hydroxide (NaOH). However, sodium

4368-405: Is not widely used in commercial processes.) Exposure systems may be classified by the optics that transfer the image from the mask to the wafer. Photolithography produces better thin film transistor structures than printed electronics , due to smoother printed layers, less wavy patterns, and more accurate drain-source electrode registration. A contact aligner, the simplest exposure system, puts

4480-690: Is obsolete. An early attempt at combining several components in one device (like modern ICs) was the Loewe 3NF vacuum tube first made in 1926. Unlike ICs, it was designed with the purpose of tax avoidance , as in Germany, radio receivers had a tax that was levied depending on how many tube holders a radio receiver had. It allowed radio receivers to have a single tube holder. One million were manufactured, and were "a first step in integration of radioelectronic devices". The device contained an amplifier , composed of three triodes, two capacitors and four resistors in

4592-431: Is the minimum feature size (also called the critical dimension , target design rule , or " half-pitch "), λ {\displaystyle \,\lambda } is the wavelength of light used, and N A {\displaystyle \,NA} is the numerical aperture of the lens as seen from the wafer. k 1 {\displaystyle \,k_{1}} (commonly called k1 factor )

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4704-456: Is then prebaked to drive off excess photoresist solvent, typically at 90 to 100 °C for 30 to 60 seconds on a hotplate. A BARC coating (Bottom Anti-Reflectant Coating) may be applied before the photoresist is applied, to avoid reflections from occurring under the photoresist and to improve the photoresist's performance at smaller semiconductor nodes such as 45 nm and below. Top Anti-Reflectant Coatings (TARCs) also exist. EUV lithography

4816-443: Is thus also called " excimer laser lithography "), which allow minimum feature sizes down to 50  nm. Excimer laser lithography has thus played a critical role in the continued advance of the Moore's Law for the last 20 years (see below ). The minimum feature size that a projection system can print is given approximately by: where C D {\displaystyle \,CD}

4928-402: Is unique in the sense it allows for the use of photoresists with metal oxides. After prebaking, the photoresist is exposed to a pattern of intense light. The exposure to light causes a chemical change that allows some of the photoresist to be removed by a special solution, called "developer" by analogy with photographic developer . Positive photoresist, the most common type, becomes soluble in

5040-461: The U.S. Army Diamond Ordnance Fuze Laboratory , which eventually merged to form the now-present Army Research Laboratory ) with the task of finding a way to reduce the size of electronic circuits in order to better fit the necessary circuitry in the limited space available inside a proximity fuze . Inspired by the application of photoresist, a photosensitive liquid used to mark the boundaries of rivet holes in metal aircraft wings, Nall determined that

5152-476: The dual in-line package (DIP), first in ceramic and later in plastic, which is commonly cresol - formaldehyde - novolac . In the 1980s pin counts of VLSI circuits exceeded the practical limit for DIP packaging, leading to pin grid array (PGA) and leadless chip carrier (LCC) packages. Surface mount packaging appeared in the early 1980s and became popular in the late 1980s, using finer lead pitch with leads formed as either gull-wing or J-lead, as exemplified by

5264-464: The krypton fluoride (KrF) laser at 248 nm wavelength and the argon fluoride laser (ArF) at 193 nm wavelength. The primary manufacturers of excimer laser light sources in the 1980s were Lambda Physik (now part of Coherent, Inc.) and Lumonics. Since the mid-1990s Cymer Inc. has become the dominant supplier of excimer laser sources to the lithography equipment manufacturers, with Gigaphoton Inc. as their closest rival. Generally, an excimer laser

5376-488: The non-recurring engineering (NRE) costs are spread across typically millions of production units. Modern semiconductor chips have billions of components, and are far too complex to be designed by hand. Software tools to help the designer are essential. Electronic design automation (EDA), also referred to as electronic computer-aided design (ECAD), is a category of software tools for designing electronic systems , including integrated circuits. The tools work together in

5488-498: The periodic table of the chemical elements were identified as the most likely materials for a solid-state vacuum tube . Starting with copper oxide , proceeding to germanium , then silicon , the materials were systematically studied in the 1940s and 1950s. Today, monocrystalline silicon is the main substrate used for ICs although some III-V compounds of the periodic table such as gallium arsenide are used for specialized applications like LEDs , lasers , solar cells and

5600-544: The small-outline integrated circuit (SOIC) package – a carrier which occupies an area about 30–50% less than an equivalent DIP and is typically 70% thinner. This package has "gull wing" leads protruding from the two long sides and a lead spacing of 0.050 inches. In the late 1990s, plastic quad flat pack (PQFP) and thin small-outline package (TSOP) packages became the most common for high pin count devices, though PGA packages are still used for high-end microprocessors . Ball grid array (BGA) packages have existed since

5712-416: The switching power consumption per transistor goes down, while the memory capacity and speed go up, through the relationships defined by Dennard scaling ( MOSFET scaling ). Because speed, capacity, and power consumption gains are apparent to the end user, there is fierce competition among the manufacturers to use finer geometries. Over the years, transistor sizes have decreased from tens of microns in

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5824-503: The very large-scale integration (VLSI) of more than 10,000 transistors on a single chip. At first, MOS-based computers only made sense when high density was required, such as aerospace and pocket calculators . Computers built entirely from TTL, such as the 1970 Datapoint 2200 , were much faster and more powerful than single-chip MOS microprocessors such as the 1972 Intel 8008 until the early 1980s. Advances in IC technology, primarily smaller features and larger chips, have allowed

5936-524: The 193 nm ArF excimer laser and liquid immersion techniques. Also termed immersion lithography , this enables the use of optics with numerical apertures exceeding 1.0. The liquid used is typically ultra-pure, deionised water, which provides for a refractive index above that of the usual air gap between the lens and the wafer surface. The water is continually circulated to eliminate thermally-induced distortions. Water will only allow NA' s of up to ~1.4, but fluids with higher refractive indices would allow

6048-413: The 1960s, the size, speed, and capacity of chips have progressed enormously, driven by technical advances that fit more and more transistors on chips of the same size – a modern chip may have many billions of transistors in an area the size of a human fingernail. These advances, roughly following Moore's law , make the computer chips of today possess millions of times the capacity and thousands of times

6160-425: The 1970s. Flip-chip Ball Grid Array packages, which allow for a much higher pin count than other package types, were developed in the 1990s. In an FCBGA package, the die is mounted upside-down (flipped) and connects to the package balls via a package substrate that is similar to a printed-circuit board rather than by wires. FCBGA packages allow an array of input-output signals (called Area-I/O) to be distributed over

6272-482: The 22 nm node (Intel) or 16/14 nm nodes. Mono-crystal silicon wafers are used in most applications (or for special applications, other semiconductors such as gallium arsenide are used). The wafer need not be entirely silicon. Photolithography is used to mark different areas of the substrate to be doped or to have polysilicon, insulators or metal (typically aluminium or copper) tracks deposited on them. Dopants are impurities intentionally introduced to

6384-513: The System/360 in 1970. SLT used silicon planar glass-encapsulated transistors and diodes. SLT uses dual diode chips and individual transistor chips each approximately 0.025 inches (0.64 mm) square. The chips are mounted on a 0.5 inches (13 mm) square substrate with silk-screened resistors and printed connections. The whole is encapsulated to form a 0.5 inches (13 mm) square module. Up to 36 modules are mounted on each card, though

6496-430: The aspect ratio approaches unity). Wet etch processes are generally isotropic in nature, which is often indispensable for microelectromechanical systems , where suspended structures must be "released" from the underlying layer. The development of low-defectivity anisotropic dry-etch process has enabled the ever-smaller features defined photolithographically in the resist to be transferred to the substrate material. After

6608-719: The circuit elements are inseparably associated and electrically interconnected so that it is considered to be indivisible for the purposes of construction and commerce. In strict usage, integrated circuit refers to the single-piece circuit construction originally known as a monolithic integrated circuit , which comprises a single piece of silicon. In general usage, circuits not meeting this strict definition are sometimes referred to as ICs, which are constructed using many different technologies, e.g. 3D IC , 2.5D IC , MCM , thin-film transistors , thick-film technologies , or hybrid integrated circuits . The choice of terminology frequently appears in discussions related to whether Moore's Law

6720-479: The components of the electronic circuit are completely integrated". The first customer for the new invention was the US Air Force . Kilby won the 2000 Nobel Prize in physics for his part in the invention of the integrated circuit. However, Kilby's invention was not a true monolithic integrated circuit chip since it had external gold-wire connections, which would have made it difficult to mass-produce. Half

6832-549: The depth of the topography on the wafer. Chemical mechanical polishing is often used to flatten topography before high-resolution lithographic steps. From classical optics, k1=0.61 by the Rayleigh criterion . The image of two points separated by less than 1.22 wavelength/NA will not maintain that separation but will be larger due to the interference between the Airy discs of the two points. It must also be remembered, though, that

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6944-473: The desktop Datapoint 2200 were built from bipolar integrated circuits, either TTL or the even faster emitter-coupled logic (ECL). Nearly all modern IC chips are metal–oxide–semiconductor (MOS) integrated circuits, built from MOSFETs (metal–oxide–silicon field-effect transistors). The MOSFET invented at Bell Labs between 1955 and 1960, made it possible to build high-density integrated circuits . In contrast to bipolar transistors which required

7056-411: The developer might be tightly controlled using jacketed (dual walled) hoses to within 0.2 °C. The nozzle that coats the wafer with developer may influence the amount of developer that is necessary. The resulting wafer is then "hard-baked" if a non-chemically amplified resist was used, typically at 120 to 180 °C for 20 to 30 minutes. The hard bake solidifies the remaining photoresist, to make

7168-402: The developer when exposed; with negative photoresist, unexposed regions are soluble in the developer. A post-exposure bake (PEB) is performed before developing, typically to help reduce standing wave phenomena caused by the destructive and constructive interference patterns of the incident light. In deep ultraviolet lithography, chemically amplified resist (CAR) chemistry is used. This resist

7280-418: The die must pass through the material electrically connecting the die to the package, through the conductive traces (paths) in the package, through the leads connecting the package to the conductive traces on the printed circuit board . The materials and structures used in the path these electrical signals must travel have very different electrical properties, compared to those that travel to different parts of

7392-541: The diffusion of impurities into silicon. A precursor idea to the IC was to create small ceramic substrates (so-called micromodules ), each containing a single miniaturized component. Components could then be integrated and wired into a bidimensional or tridimensional compact grid. This idea, which seemed very promising in 1957, was proposed to the US Army by Jack Kilby and led to the short-lived Micromodule Program (similar to 1951's Project Tinkertoy). However, as

7504-456: The distance between two features can also change with defocus. Resolution is also nontrivial in a two-dimensional context. For example, a tighter line pitch results in wider gaps (in the perpendicular direction) between the ends of the lines. More fundamentally, straight edges become rounded for shortened rectangular features, where both x and y pitches are near the resolution limit. For advanced nodes, blur, rather than wavelength, becomes

7616-537: The early 1970s to 10 nanometers in 2017 with a corresponding million-fold increase in transistors per unit area. As of 2016, typical chip areas range from a few square millimeters to around 600 mm , with up to 25 million transistors per mm . The expected shrinking of feature sizes and the needed progress in related areas was forecast for many years by the International Technology Roadmap for Semiconductors (ITRS). The final ITRS

7728-541: The entire die rather than being confined to the die periphery. BGA devices have the advantage of not needing a dedicated socket but are much harder to replace in case of device failure. Intel transitioned away from PGA to land grid array (LGA) and BGA beginning in 2004, with the last PGA socket released in 2014 for mobile platforms. As of 2018 , AMD uses PGA packages on mainstream desktop processors, BGA packages on mobile processors, and high-end desktop and server microprocessors use LGA packages. Electrical signals leaving

7840-580: The equivalent of millions of gates and operate at frequencies up to 1 GHz . Analog ICs, such as sensors , power management circuits , and operational amplifiers (op-amps), process continuous signals , and perform analog functions such as amplification , active filtering , demodulation , and mixing . ICs can combine analog and digital circuits on a chip to create functions such as analog-to-digital converters and digital-to-analog converters . Such mixed-signal circuits offer smaller size and lower cost, but must account for signal interference. Prior to

7952-430: The fabrication of transistors using photographic techniques and adopted the term "photolithography" to describe the process, marking the first published use of the term to describe semiconductor device patterning. Despite the fact that photolithography of electronic components concerns etching metal duplicates, rather than etching stone to produce a "master" as in conventional lithographic printing, Lathrop and Nall chose

8064-545: The field of electronics by enabling device miniaturization and enhanced functionality. Integrated circuits are orders of magnitude smaller, faster, and less expensive than those constructed of discrete components, allowing a large transistor count . The IC's mass production capability, reliability, and building-block approach to integrated circuit design have ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. ICs are now used in virtually all electronic equipment and have revolutionized

8176-574: The first volume uses of hybrid thick-film technology . SLT replaced the earlier Standard Modular System , although some later SMS cards held SLT modules. SLT had several updates during its life, the last being the Monolithic System Technology ( MST ) which replaced the single transistors of SLT with small-scale integrated circuits that held four or five transistors. MST was used in the System/370 , which began to replace

8288-412: The foundry model, fabless companies (like Nvidia ) only design and sell ICs and outsource all manufacturing to pure play foundries such as TSMC . These foundries may offer IC design services. The earliest integrated circuits were packaged in ceramic flat packs , which continued to be used by the military for their reliability and small size for many years. Commercial circuit packaging quickly moved to

8400-568: The highest-speed integrated circuits. It took decades to perfect methods of creating crystals with minimal defects in semiconducting materials' crystal structure . Semiconductor ICs are fabricated in a planar process which includes three key process steps – photolithography , deposition (such as chemical vapor deposition ), and etching . The main process steps are supplemented by doping and cleaning. More recent or high-performance ICs may instead use multi-gate FinFET or GAAFET transistors instead of planar ones, starting at

8512-602: The idea to the public at the Symposium on Progress in Quality Electronic Components in Washington, D.C. , on 7 May 1952. He gave many symposia publicly to propagate his ideas and unsuccessfully attempted to build such a circuit in 1956. Between 1953 and 1957, Sidney Darlington and Yasuo Tarui ( Electrotechnical Laboratory ) proposed similar chip designs where several transistors could share

8624-421: The key resolution-limiting factor. Minimum pitch is given by blur sigma/0.14. Blur is affected by dose as well as quantum yield, leading to a tradeoff with stochastic defects, in the case of EUV. As light consists of photons , at low doses the image quality ultimately depends on the photon number. This affects the use of extreme ultraviolet lithography or EUVL, which is limited to the use of low doses on

8736-421: The late 1990s, radios could not be fabricated in the same low-cost CMOS processes as microprocessors. But since 1998, radio chips have been developed using RF CMOS processes. Examples include Intel's DECT cordless phone, or 802.11 ( Wi-Fi ) chips created by Atheros and other companies. Modern electronic component distributors often further sub-categorize integrated circuits: The semiconductors of

8848-421: The light intensity to be uniform across an entire wafer, and the mask to align precisely to features already on the wafer. As modern processes use increasingly large wafers, these conditions become increasingly difficult. Research and prototyping processes often use contact or proximity lithography, because it uses inexpensive hardware and can achieve high optical resolution. The resolution in proximity lithography

8960-442: The lithography tools (a significant challenge). An inert gas atmosphere can sometimes be used as a substitute for a vacuum, to avoid the need for hard plumbing. Furthermore, insulating materials such as silicon dioxide , when exposed to photons with energy greater than the band gap, release free electrons and holes which subsequently cause adverse charging. Optical lithography has been extended to feature sizes below 50 nm using

9072-512: The machine, but modern machines do not use tracks. If organic or inorganic contaminations are present on the wafer surface, they are usually removed by wet chemical treatment, e.g. the RCA clean procedure based on solutions containing hydrogen peroxide . Other solutions made with trichloroethylene, acetone or methanol can also be used to clean. The wafer is initially heated to a temperature sufficient to drive off any moisture that may be present on

9184-408: The mask onto the wafer many times, changing the position of the wafer with every projection, to create the complete pattern, fully patterning the wafer. The difference between steppers and scanners is that, during exposure, a scanner moves the photomask and the wafer simultaneously, while a stepper only moves the wafer. Contact, proximity and projection Mask aligners preceded steppers and do not move

9296-464: The material beneath, which was then chemically etched in an acid bath to produce a printing plate. The light-sensitivity of bitumen was very poor and very long exposures were required, but despite the later introduction of more sensitive alternatives, its low cost and superb resistance to strong acids prolonged its commercial life into the early 20th century. In 1940, Oskar Süß created a positive photoresist by using diazonaphthoquinone , which worked in

9408-443: The minimum feature size that can be formed in the photoresist. Photolithography is the most common method for the semiconductor fabrication of integrated circuits ("ICs" or "chips"), such as solid-state memories and microprocessors . It can create extremely small patterns, down to a few nanometers in size. It provides precise control of the shape and size of the objects it creates. It can create patterns over an entire wafer in

9520-433: The number of MOS transistors in an integrated circuit to double every two years, a trend known as Moore's law. Moore originally stated it would double every year, but he went on to change the claim to every two years in 1975. This increased capacity has been used to decrease cost and increase functionality. In general, as the feature size shrinks, almost every aspect of an IC's operation improves. The cost per transistor and

9632-469: The opposite manner: the coating was initially insoluble and was rendered soluble where it was exposed to light. In 1954, Louis Plambeck Jr. developed the Dycryl polymeric letterpress plate, which made the platemaking process faster. Development of photoresists used to be carried out in batches of wafers (batch processing) dipped into a bath of developer, but modern process offerings do development one wafer at

9744-471: The order of 20 photons/nm . This is due to fewer photons for the same energy dose for a shorter wavelength (higher energy per photon). With fewer photons making up the image, there is noise in the edge placement. The stochastic effects would become more complicated with larger pitch patterns with more diffraction orders and using more illumination source points. Secondary electrons in EUV lithography aggravate

9856-489: The pattern in the photoresist is created by exposing it to light — either directly by projection through a lens , or by illuminating a mask placed directly over the substrate, as in contact printing . The technique can also be seen as a high precision version of the method used to make printed circuit boards . The name originated from a loose analogy with the traditional photographic method of producing plates for lithographic printing on paper; however, subsequent stages in

9968-429: The pattern is transferred onto the substrate through etching , chemical vapor deposition , or ion implantation processes. Ultraviolet (UV) light is typically used. Photolithography processes can be classified according to the type of light used, including ultraviolet lithography, deep ultraviolet lithography, extreme ultraviolet lithography (EUVL) , and X-ray lithography . The wavelength of light used determines

10080-409: The photomask nor the wafer during exposure and use masks that cover the entire wafer. Immersion lithography scanners use a layer of Ultrapure water between the lens and the wafer to increase resolution. An alternative to photolithography is nanoimprint lithography . The maximum size of the image that can be projected onto a wafer is known as the reticle limit. The image for the mask originates from

10192-604: The photoresist on the mask is exposed, the chrome can be etched away, leaving a clear path for the illumination light in the stepper/scanner system to travel through. The ability to project a clear image of a small feature onto the wafer is limited by the wavelength of the light that is used, and the ability of the reduction lens system to capture enough diffraction orders from the illuminated mask. Current state-of-the-art photolithography tools use deep ultraviolet (DUV) light from excimer lasers with wavelengths of 248 (KrF) and 193 (ArF) nm (the dominant lithography technology today

10304-496: The primary tools in microelectronics production, and has enabled minimum features sizes in chip manufacturing to shrink from 800 nanometers in 1990 to 7 nanometers in 2018. From an even broader scientific and technological perspective, in the 50-year history of the laser since its first demonstration in 1960, the invention and development of excimer laser lithography has been recognized as a major milestone. The commonly used deep ultraviolet excimer lasers in lithography systems are

10416-421: The process have more in common with etching than with traditional lithography. Conventional photoresists typically consist of three components: resin, sensitizer, and solvent. The root words photo , litho , and graphy all have Greek origins, with the meanings 'light', 'stone' and 'writing' respectively. As suggested by the name compounded from them, photolithography is a printing method (originally based on

10528-439: The process. The procedure described here omits some advanced treatments, such as thinning agents. The photolithography process is carried out by the wafer track and stepper/scanner, and the wafer track system and the stepper/scanner are installed side by side. Wafer track systems are also known as wafer coater/developer systems, which perform the same functions. Wafer tracks are named after the "tracks" used to carry wafers inside

10640-497: The project was gaining momentum, Kilby came up with a new, revolutionary design: the IC. Newly employed by Texas Instruments , Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working example of an integrated circuit on 12 September 1958. In his patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material … wherein all

10752-402: The same die. As a result, they require special design techniques to ensure the signals are not corrupted, and much more electric power than signals confined to the die itself. Photolithography Photolithography (also known as optical lithography ) is a process used in the manufacturing of integrated circuits . It involves using light to transfer a pattern onto a substrate, typically

10864-426: The semiconductor industry's need for both higher resolution (to produce denser and faster chips) and higher throughput (for lower costs), lamp-based lithography tools were no longer able to meet the industry's high-end requirements. This challenge was overcome in 1982 when excimer laser lithography was proposed and demonstrated at IBM by Kanti Jain. Excimer laser lithography machines (steppers and scanners) became

10976-474: The size of the transistors. Such techniques are collectively known as advanced packaging . Advanced packaging is mainly divided into 2.5D and 3D packaging. 2.5D describes approaches such as multi-chip modules while 3D describes approaches where dies are stacked in one way or another, such as package on package and high bandwidth memory. All approaches involve 2 or more dies in a single package. Alternatively, approaches such as 3D NAND stack multiple layers on

11088-427: The speed of the computer chips of the early 1970s. ICs have three main advantages over circuits constructed out of discrete components: size, cost and performance. The size and cost is low because the chips, with all their components, are printed as a unit by photolithography rather than being constructed one transistor at a time. Furthermore, packaged ICs use much less material than discrete circuits. Performance

11200-560: The stochastic characteristics. Historically, photolithography has used ultraviolet light from gas-discharge lamps using mercury , sometimes in combination with noble gases such as xenon . These lamps produce light across a broad spectrum with several strong peaks in the ultraviolet range. This spectrum is filtered to select a single spectral line . From the early 1960s through the mid-1980s, Hg lamps had been used in lithography for their spectral lines at 436 nm ("g-line"), 405 nm ("h-line") and 365 nm ("i-line"). However, with

11312-410: The temperature at 120 °C. The wafer is covered with photoresist liquid by spin coating . Thus, the top layer of resist is quickly ejected from the wafer's edge while the bottom layer still creeps slowly radially along the wafer. In this way, any 'bump' or 'ridge' of resist is removed, leaving a very flat layer. However, viscous films may result in large edge beads which are areas at the edges of

11424-481: The term "photolithography" over "photoetching" because the former sounded "high tech." A year after the conference, Lathrop and Nall's patent on photolithography was formally approved on June 9, 1959. Photolithography would later contribute to the development of the first semiconductor ICs as well as the first microchips. A single iteration of photolithography combines several steps in sequence. Modern cleanrooms use automated, robotic wafer track systems to coordinate

11536-415: The uppermost layer of the substrate in the areas that are not protected by photoresist. In semiconductor fabrication , dry etching techniques are generally used, as they can be made anisotropic , in order to avoid significant undercutting of the photoresist pattern. This is essential when the width of the features to be defined is similar to or less than the thickness of the material being etched (i.e. when

11648-418: The use of limestone printing plates) in which light plays an essential role. In the 1820s, Nicephore Niepce invented a photographic process that used Bitumen of Judea , a natural asphalt, as the first photoresist . A thin coating of the bitumen on a sheet of metal, glass or stone became less soluble where it was exposed to light; the unexposed parts could then be rinsed away with a suitable solvent, baring

11760-569: The wafer or photomask with increased resist thickness whose planarization has physical limits. Often, Edge bead removal (EBR) is carried out, usually with a nozzle, to remove this extra resist as it could otherwise cause particulate contamination. Final thickness is also determined by the evaporation of liquid solvents from the resist. For very small, dense features (< 125 or so nm), lower resist thicknesses (< 0.5 microns) are needed to overcome collapse effects at high aspect ratios; typical aspect ratios are < 4:1. The photoresist-coated wafer

11872-432: The wafer surface; 150 °C for ten minutes is sufficient. Wafers that have been in storage must be chemically cleaned to remove contamination . A liquid or gaseous "adhesion promoter", such as Bis(trimethylsilyl)amine ("hexamethyldisilazane", HMDS) , is applied to promote adhesion of the photoresist to the wafer. The surface layer of silicon dioxide on the wafer reacts with HMDS to form tri-methylated silicon-dioxide,

11984-416: The wavelength, and increasing the numerical aperture (to achieve a tighter focused beam and a smaller spot size). However, this design method runs into a competing constraint. In modern systems, the depth of focus is also a concern: Here, k 2 {\displaystyle \,k_{2}} is another process-related coefficient. The depth of focus restricts the thickness of the photoresist and

12096-400: The world of electronics . Computers, mobile phones, and other home appliances are now essential parts of the structure of modern societies, made possible by the small size and low cost of ICs such as modern computer processors and microcontrollers . Very-large-scale integration was made practical by technological advancements in semiconductor device fabrication . Since their origins in

12208-401: Was a 16-transistor chip built by Fred Heiman and Steven Hofstein at RCA in 1962. General Microelectronics later introduced the first commercial MOS integrated circuit in 1964, a 120-transistor shift register developed by Robert Norman. By 1964, MOS chips had reached higher transistor density and lower manufacturing costs than bipolar chips. MOS chips further increased in complexity at

12320-441: Was developed at Fairchild Semiconductor by Federico Faggin in 1968. The application of MOS LSI chips to computing was the basis for the first microprocessors , as engineers began recognizing that a complete computer processor could be contained on a single MOS LSI chip. This led to the inventions of the microprocessor and the microcontroller by the early 1970s. During the early 1970s, MOS integrated circuit technology enabled

12432-514: Was issued in 2016, and it is being replaced by the International Roadmap for Devices and Systems . Initially, ICs were strictly electronic devices. The success of ICs has led to the integration of other technologies, in an attempt to obtain the same advantages of small size and low cost. These technologies include mechanical devices, optics, and sensors. As of 2018 , the vast majority of all transistors are MOSFETs fabricated in

12544-480: Was the largest single consumer of integrated circuits between 1961 and 1965. Transistor–transistor logic (TTL) was developed by James L. Buie in the early 1960s at TRW Inc. TTL became the dominant integrated circuit technology during the 1970s to early 1980s. Dozens of TTL integrated circuits were a standard method of construction for the processors of minicomputers and mainframe computers . Computers such as IBM 360 mainframes, PDP-11 minicomputers and

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